Harcourt Arboretum

The first of our practical events in 2015 was held on Saturday 28th November at Harcourt Arboretum, situated in the village of Newnham Courtney, a mere 20-minute bus ride from the centre of Oxford.

Harcourt Arboretum belongs to the University of Oxford, and alongside the Botanic Gardens it houses the University’s collection of living floral specimens. Arboretum is a Latin word, which literally translates to “a place grown with trees”. Harcourt is, effectively, a living catalogue of the world’s trees! The site is open to the public, who are charged entry, but students of the university have free access. During the winter months, however, the gates are only open on weekdays, often making it difficult for students to visit in-between their busy academic schedules. Weekend volunteering provides a fantastic opportunity to experience the arboretum in the absence of other visitors, whilst contributing to its management and learning from the team responsible for its upkeep.

On this occasion we were helping to coppice hazel: a woody plant with flexible stems, commonly used in the construction of fencing and woven household items. Hazel is generally harvested by coppicing, removing the stems when they have grown to several metres tall, whilst leaving the stools (stumps) intact. This not only allows repeated coppicing of regrowth for generations, it also extends the life of the tree to as much as several hundred years!

At Harcourt, coppicing is performed on different sections of hazel woodland on rotation, allowing a permanent mature habitat to be maintained: one which is crucial for many British faunal species, including the caterpillars of many moths which feed on the leaves, birds which feed on the nuts, and the endangered Hazel Dormouse which calls these woodlands its home.

To begin our day, Guy the arborist cut the hazel around 10 centimetres off of the ground using chainsaw, producing long thin branches, which we could then strip of outgrowths using billhooks and fashion into materials for fence building. Those with a diameter of greater than around 5 centimetres were chopped at around chest height, forming stakes which could then be used as posts. Any branches smaller than this were left at a length of around 3 metres, to be used as the binders which join the posts.

The remaining hazel stools can be left to regrow and after several years will be large enough for the process to be repeated. Covering them in the brash (unused branches) left over from the coppicing aids this process by reducing grazing by animals such as deer and rabbits, and hence increases the chances of growth.

We were taught the most effective method for using billhooks: holding the branch across the body, resting on the thigh of one leg and swinging the billhook past the side of the body. Several hours of swinging – and some very, very bruised legs – later we had a pile of around 30 stakes and almost twice as many binders to be tied up and stored in preparation for our next visit.

We returned to the arboretum in 2016 on Saturday 23rd January, to assist with the building of a natural boundary fence around the visitor car park, using the very materials which we had harvested the previous term!

The natural fence integrates living trees and shrubs, which will continue to grow, allowing it to become increasingly dense over time. This removes the necessity for conventional metal fencing, plus it is more efficient, more aesthetically pleasing and much more wildlife friendly!

The rangers at the arboretum had already planted a line of small saplings at around 1 metre high, including species such hawthorn and beech, to be woven into the fence. Our job was to drive in our stakes, using a mallet, at equally spaced intervals between these trees. By then cutting the trees at the base, leaving only a few millimetres of bark and vascular tissue attaching it to the roots, we pushed them over and wound them between the stakes. To complete the living fence, we wound our hazel binders between the protruding tops of the stakes, overlapping them incrementally to provide a sturdy scaffolding around which the saplings can grow.

As the trees in this fence grow they will produce a hedge which is impermeable to people and livestock (especially as hawthorn is so spikey), providing a secure border for the grounds, which also supports wildlife and forms a corridor habitat for many animal species. Once the fence has grown to a sufficient density, the arboretum team will be able to remove the existing metal wire fence from the roadside, leaving only a natural boundary. Of course, our fence will require careful maintenance such thinning and further weaving in the future to ensure that it maintains its valuable properties. Perhaps this will be an activity which we can return to assist with as a group in the future!

Considering the amount of untrained billhook swinging that went on last year it’s remarkable that the only injury was me nearly fainting when we applied an icepack to my swollen wrist, following too much vigorous chopping! My predicament was quickly remedied, however, by the consumption of a doughnut, kindly provided by the arborist Luke.

This academic year we will be returning to the arboretum to help them with activities such coppicing and young woodland thinning so come along and get involved! Find out more at the fresher’s fair, or get in touch with the ConSoc team!